Hydrocarbon conversion system



M. SUTTON E-rAl.

HYDROCARBON CONVERSION SYSTEM Filed Dec. 4, 1942 July 3, 1945.

Patented July 3, 1945 Y UNIT-ED STATES mnocAnaoN CONVERSION SYSTEM Mack Sutton, Hammond, and Cecil w. Nysewander, Highland, Ind., -assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application December 4, 1942, Serial No. v467,824

4 Claims. (Cl. 26o-683.5)

This invention relates to a hydrocarbon conversion system employing an aluminum halidehydrocarbon complex catalyst and the invention pertains more particularly to an improved method and means for the introduction of make-up I aluminum chloride thereto. The invention is primarily directed to improvements in a system for somerlzing light hydrocarbons but many features thereof are applicable for effecting alkylation, disproportionation, polymerization and "other 'carbon complexes.

In light hydrocarbon conversion systems em-'f ploying a liquid aluminum halide-hydrocarbon complex as a catalyst, the catalyst complex eventually loses its activity to a considerable extent audit is necessary to either replace the complex by a fresher or more active complex or to add additional aluminum chloride to the complex during the course of the reaction. 'lhe addition of serious problems. It is necessary to obtain rapid and intimate dispersion of the added aluminum chloride throughout the complex' mass in the reactor. It is necessary to prevent line Dluging in the make-up aluminum chloride system. It is necessary to avoid the introduction of contaminants. An object of our invention is to provide a solution of these problems.

vIt has been proposed to introduce such make- 'up aluminum chloride as a solution in, charging stock, but charging stock usually will not retain an appreciable amountof aluminum chloride in solution, it usually contains dissolved hydrogen chloride which would produce undesirable vigorous reactions (resulting in coking, etc.) before the charging stock meets the body of, complex mass and it is usually introduced at a dillerent stage y from that at which it is desired to introduce the make-up aluminum chloride. Solvents for makeup aluminum chloride are undesirable because they contaminate the reaction system and result introducing make-up aluminum chloride 03ers a vexatious problem of maintaining relatively high v turbulence at all timesbecauseif the slurryis allowed to remain quiescent for any mme amount of time the aluminum chloride settles' out lsunic'suses aplugginl of lines and valves. The

' obiectof our invention is tc avoid the diillculties in this connection which have heretofore conmethod and means for introducing make-up aluminum chloride.

We have discovered that make-up aluminum chloride may be added to ahigh pressure reaction supplied in the form of a paste, particularly when lo the paste is prepared from a complex which is conversions effected by aluminum halide-hydrostill at least partially active. We have found that about V2 to 2 pounds or more of aluminum chloride can be incorporated in one pound.. of aluminum chloride-hydrocarbon complex to pro- -ls duce a paste which is of approximately the consistency of ordinary tooth-paste. This paste is ,radically different from solutions because the alu. minum chloride particles remain substantially undlssolved so that they may be dispersedin solid go form throughout the complex in the reactor. The make-up aluminum chloride .tocatalyst complex in a reactor system maintained under substantial superatniospheric pressure has given rise to many paste radically diners from a slurry in that it prevents any settling or sedimentation problems. We have found that the aluminum chloride-ccmplex not only keeps the aluminum chloride partigs cles in a relatively permanent suspension but it also acts as a lubricant to facilitate the injection thereof through conduits and distributors in the l vreact'ion'chamber.

Slurrte's and solutionsmy be handled by or- 30 dinary pumps but our paste requires a dlilerent at ably the injection is eifect'ed by hydraulic presl sure, the pressure in theA conversion system serving to illectcomplex into' the paste'mixerand-to displace pressuring' iluid therefrom while the pumping of the pressuring fluid in a reverse di- 40 rection serves to lntroducepaste from the mixer to the high pressure conversion reactor.

The invention will be more clearly. understood from theI following detailed description read in conjunction with the .accompanying drawing in undesirable luy-products. 'me nun-y method of f wm mm a Pm if he Mmm d "mh is asehematic now diagram ,of a light naphtha isomerization system employing our new method :1nd means for supplying make-up aluminum chlo.

IO Theprocessillustrutedinthedrawiligisisomerization of debutanised light nsphtha hsvlng'4 a 90% point below about 180' F. and l'il'cilirablyv not higher than about' 16o' l'. such acharginl stockv consists essentially of -pentsnes and hexironted the art andtoprovide a rsdicsllynew fgsnesbutitmsycontslnasmsllsmmt oisromatics'and a somewhat larger amount of naphthenes. This processmay be operated for the production of an aviation fuel or blending stock called isomate or it may be operated for the production of neohexane, isopentane, etc. Our invention is equally applicable to systems for isomerizing naphthenes, i. e., for converting alkyl cyclopentanes to cyclohexanes and methyl cyclohexanes. It is also equally applicable to the isomerization of normal butane to isobutane except that in such process it is desirable to operate in the absence of added hydrogen. Many features of our invention are applicable to other processes employing aluminum chloride hydrocarbon complexes such as processes for polymerizing oleiins, processes for alkylating olens with isoparaiins or aromatics, etc.

In the specic example herein set forth the charging stock from source I may be introduced by pump II through lines I2 and I3 to the upper part of absorber tower I4. Recycled gases containing hydrogen chloride are introduced at the base of this tower through line I5. Gases denuded ofv hydrogen chloride are removed from the top of the towerl through line II.Y Make-up hydrogen chloride may be added from line I1 either to'the base of tower I4 or to line I8 leaving the base of this tower. The charging stock which now contains about 2 to 10%, for example about 6%, hydrogen chloride is introduced by pump I9 throughheater 20 into the A reactor 2|. Catalyst complex may be introduced into reactor 2| through line 22 and substantially spent catalyst complex may be withdrawn from the reactor through line 23.

The catalyst complex is preferably an aluminum halide hydrocarbon complex of the type described in U. S, Patents 2,260,279` and 2,300,249, etc. Tower 2l may be 15 to 40 feet in height and the catalyst level may -be about two-thirds to three-fourths of the distance fromthe tower bottom to the tower top. The reactorI is preferably operated under a pressure of the order of :about 850 poundsl per square inch although pressures may range from a few hundred to severalthousandpounds. The temperature in this reactor is preferably of the order of 250 to 300 F. although it may range from about 100 F. to about 400 F. The space velocity employed may beabout .1 to but is preferably about 0.5 to 2 volumesof liquid feed per hour per volume of liquid catalyst complex in the tower.

In the drawing we have shown the hydrogen chloride introduced into the reactor at an intermediate point"instead of at the -bottom thereof. Hydrogen is introduced into the reactor through line 24 at a point substantially Ibelow the point at which hydrogen chloride is introduced thereto so that that -portion of the reactor between the point of hydrogen chloride inlet and the point'of hydrogen inlet may constitute a stripping zone 25. Hydrogen may be introduced into the system at the rate 'of about 50 to 300, usually about 150 to 200 cubic feet (measured standard conditions) per barrel of stock charged and this h'yl drogen may beproduced from hydrocarbons in the refinery 'and thus be contaminated with small I amounts of carbon monoxide. As the hydrogen passes upwardly in stripping zone 25 of reaction A"chamber-"ill any carbon monoxide in the hydrogen is scrubbed out of it by the downowiiig catalyst complex. At the same time the upiiowing we thus purify the introduced hydrogen by means of spent complex and we simultaneously recover from the spent complex valuable hydrogen chloride which would otherwise be withdrawn through line 23 with spent catalyst. When there are no objectionable contaminants in the hydrogen, however, the several streams may all be introduced near the base of the reactor.

. The total liquid-vapor-gas stream from the top of reactor 2| passes through cooler 26 to a low point in reactor 21. Make-up aluminum chloride from line 28 and recycled catalyst from line 29 are introduced into reactor 21 through line 30. Here again the catalyst level is maintained at a relatively high point in the reactor and the liquidvapor-gas stream passes upwardly through the reactor at the space velocity hereinabove stated, the space Velocity referring to the total catalyst in both reactors. Reactor 21 is preferably operated within the approximate temperature range of 200 to 250 F. Catalyst from the base of this reactor is withdrawn by pump 3l for introduction by the line 22 to the reactor 2 I.

The product stream from the top of reactor 21 is introduced by line 32 to warm settler 33 from which settled catalyst may be returned to reactor 21 by line 28 as hereinabove described. The product stream leaves settler 33 through line 34, is cooled in cooler 35 and then passes through pressure reduction valve 36 to cool settler 31 which may operate at a pressure of about 300 to 350 pounds per square inch and at substantially atmospheric temperature. Catalyst material settled out in the cool settler may -be returned by pump 38 to reactor 21. Gases,'chiefly hydrogen and hydrogen chloride with small amounts of methane, ethane, etc. leave the top of settler 31 through line 39 and are recycled by line I5 to the base of absorber I4. The liquid hydrocarbon reaction products are introduced from settler 31 by valve 40 to the upper part of hydrogen chloride stripper 4I which is provided with heating means 42 at its base and which may :be provided with renux means (not shown)` at its top, Hydrogen chloride and light gases are thus stripped out of -the products and are withdrawn through line 42 to line I5 for recycling to absorber I4.

The stripped products from the bottom of stripper 4I may be neutralized with a caustic solution and washed with water in suitable mixing and settling systems (not shown). It may then be introduced by line 43 to fractionating tower 4,4 which is provided with suitable reiiux means 45 at its top and suitable reboiler means 4Iiv at its base. Neohex'ane and. lighter hydrocarbons may be taken overhead through line 41 to stabilizer 48 which is likewise provided with suitable reilux and reboiler means, the stabilizer gases being withdrawn through line 49 and the isomate rich in neohexane being withdrawn through line 50.'

A part.V of the heavier hydrocarbons withdrawn as a sidestream from the lower part-of lfractionator 44 may be returned by pump 5I, cooler -52 and line I 3 to the top of absorber I4. When a sulcient amount of oil is thus recycled tothe ab- Asorber for recovering the hydrogen chloride from recycled gases introducedA through line 1.5, we

.may introduce the feed stock through line 53 directly into reactor 2| below the point at which order to provide liquid scrubbing zone inthe hydrogen` acts as a stripping gas for recovering' ffhydrogen chloride. By employing this countercurrent scrubbingzone at the base of the reactor "feed stock' scrubs hydrogen chloride reactor 2llBy this procedure Vthe introduced from spent catalyst t as said catalyst movesdownwardlyjto discharge line 23 and at the same time any catv alyst poisons which might be present in the feed stock are extracted therefrom by the downwardly moving spent complex. Thus we may utilize not only the introduced hydrogen but also the introduced charging stock for recovering valuable materials from spent catalyst and in both cases any impurities in the introduced ingredients will be scrubbed out of them before they reach that portion of the reaction chamber in which the isomerization is effected.

Oui` preferred vehicle for preparing make-up aluminum chloride-complex paste is active catalyst complex from the. conversion system itself. Such complex may be withdrawn from theB reactor 21 through line 51. Alternatively, or in addition to such complex. we may employ settled complex from line 29 introduced by line 58 to line 51 or we may employ catalyst or complex introduced by pump 36 through lineA 59 to line 51.

' Even though the catalyst which leaves the A reactor 2| through line 23 may be substantially spent as far as the isomerization reaction is conpressuring iiuid intov tank 6l. The aluminumchloride inlet of mixer 55 is 'then sealed and valve 54 in line 51 is opened to permit the complex (or complex-forming liquid) from any of the sources hereinabove designated to enter mixer 55 and displace further amounts of the naphtha or pressuring fluid. The amount of complex introduced may be readily determined by simply gauging the'amount of naphtha or other liquid displaced to tank 6I. When the required amount of complex has been introduced, the mixing device 68 is operated by suitable driving means 69 to intimately mix the aluminum chloride with the introduced complex and to form a paste about the consistency of .ordinary tooth-paste.

This paste is stable and may stand indefinitelyv without tendency of aluminum chloride particles to settle out. yIt is possible that there may be a loose chemical combination of the aluminum cerned, it may still be employed as a vehicle for making our aluminum chloride-complex paste and we may thus withdraw about one-third of the spent catalyst sludge through line 23a. to line 5l for preparing ourv aluminum chloridecomplex paste.

It is not essential that the `paste be prepared lfrom materials which are by-products o f the conversion itself (although this is usually preferred) and complex-forming hydrocarbons may n be introduced into the system from line 60 to line 51. When complex-forming hydrocarbons are introduced through line 60, it may be desirable to introduce-enough hydrogen chloride into complex-paste mixer 55 to expedite complex formation prior tol or during the preparation of the aluminum chloride paste itself. This added hydrogen chloride may be introduced'at a low point in the paste mixer through a suitable line (not shown) and any unconsumed' hydrogen chloride may be withdrawn from the top of the mixer through a suitable line (not shown) In a 5000 barrel per day isomerization plant the make-up aluminum chloride requirements may be of the general order of 300 pounds per hour' although it should be understood that the precise amount of aluminum chloride will depend 0n the quality or activity of the aluminum chloride itself, the nature of the stock charged, the extent of conversion to be effected, etc. In a specific example, we may withdraw-about 12 gallons of complex per hour to one or more complex-paste mixers 55 for making up a paste with the approximately 300 pounds per hour of aluminum chloride. A preferred procedure for making up. complex will now be described in greater detail.

Associated wtih mixer 55 is a storage tankl6i for naphtha or inert pressuring fluid. Such fluid may be introduced through line 62, valve 63,

pump 64 and valve 65 into mixer 55. Alternatively pump 64 may be stopped, valves 63 and 65 may be closed and this pressuring fluid may troduced into the mixer through line or hopper 56. thereby displacing a part of the naphtha or chloride particles with the complex but at any rate the aluminum chloride is intimately and uniformly dispersed throughout the complex in the resulting paste. This paste should contain about 80 to 90% or more of aluminum chloride,

about 87 or 88% being preferred. A fresh complex may be associated with more hydrocarbon material than a more spent complex; thus 2 pounds' of added make-up aluminum chloride to" one pound of fresh complex gave about 88 weight percent aluminum chloride in the resulting paste, while about 1.6 pounds of added makeup to one pound of a used complex gave about 8'1 weight percent aluminum chloride in the resulting paste. The paste may be prepared at about room temperature, or at temperatures up to 200 F. or more. Paste mixtures prepared at the higher temperatures are more fluid for a `given amount of aluminum chloride, or they carry a larger amount of aluminum chloride for a given consistency. The consistency does not appear to change on standing, at least for periods of a week or more. y

After the complex has thus been prepared. valve 66 is closed, valves 63 and 65 are opened and pump 64 is operated-toforce the naphtha or pressuring fluid back into mixer thus displacing the paste therefrom and forcing said paste either through line 28 and line 30 to the B reactor 21 or through line 28' and line 22 to the A reactor 2l.` Ordinarily we prefer to introduce the paste into B reactor 21 andto transfer complex from the base of the B reactor to an intermediate point in the A reactor by means of pump 3l. When the gauge on tank 6| indicates that substantially all of the complex-paste has been displaced from mixer 55, anotherbatch of paste is prepared in the manner hereinabove described.

While we have described a specic example of our invention as applied to an isomerization system it should be understood that the invention i is not limited to the 'specific details hereinabove recited since many modifications and alternatives' will be apparent to those skilled in the art from' the above detailed description.

We claim: i

1. Themethod of introducing make-up aluminum chloride into an aluminum chloride hydrocarbon conversion zone operating at superatmospheric pressure which method comprises withdrawing complex from said zone to a mixing zone thereby displacing a. pressuring fluid from said mixing zone. adding make-up aluminum chloride to said mixing zone in amounts sufficient to form a paste in said complex, mixing said aluminum chloride'with said complex tov form said with said complex in said mixing zone whereby D said material is incorporated in the complex. and transferring said complex with catalyst material incorporated therein back into said superatmospheric pressure conversion zone by reintroduoing pressuring uid into said mixing zone under vsufticient pressure to effect such transfer.

3. The method of claim 2 wherein the catalyst material is solid aluminum chloride.

4. The method of claim 2 wherein the catalyst material is solid aluminum chloride and the proportions thereof are within the approximate range of 1/2 to 2 pounds of aluminum chloride per pound of complex admixed therewith in the mixing zone.

MACK SUTTON. CECIL W. NYSEWANDER. 

